de bellescize



Aug." 23, 927. ,686

H. J. J. M. DE R. DE BELLESCIZE WIRELESS TELEGRAPH STATION Filed Aug. 29, 1921 2 Sheets-Sheet 2 K "x y F 6 a l l l .JJLDER D8 BELLESCIZE @391 his Patented Aug. 23, 1927.

UNITED STATES tenses HENRI JEAN JOSEPH MARIE DE REGNAULD DE IBELLESCIZE, OF TOULON', FRANCE.

WTRELESS-TELEGRAPH STATION.

Application filed. August 29, 1921, Serial No. 496,532, and in France January 22, 1919.

(GRANTED UNDER THE PRQVISIONS 013 THE ACT 0. 3 MARCH 3, 1921, 41 STAT. L, 1313.)

This invention relates to an improved system for wireless telegraphy working on the duplex principle. I

A system of the character just referred to comprises a transmitting station and several receiving stations, all these stations being arranged so as to be capable of operating simultaneously. and more particularly the aerials and the high and low frequency circuits of the receiving stations being so chosen that the-operation thereof will not be disturbed by the oscillations emanating from the transmitting station which is near by. For the greater convenience of service, the apparatus serving for the transmission, and those intended for the listening to or registration oi the received signals. are arranged in the same building. Up to the present, it has been customary to leave a considerable distance (about 30 km.) between the transmitting station and a receiving station pertaining to the same duplex system. so as to prevent the call-listening receiver from being disturbed or stopped by the radiation from the transmitter. Moreover, the intensity of the received signals was rather weak. Under these conditions. the most practical connection between a transmitting station and. a receiving station belonging to the same system consisted in a, connecting line, by means of which it was possible to actuate the transmitting station at a. distance from the receiving station.

Fig. 1 is a diagrammatic showing of a known system.

Fig. 2 is the showing of a duplex system.

Fig. 3 is the showing of a system using several receivers.

Fig. 4: gives a diagrammatic explanation of the operation.

Figs. 5 to 7 show modifications yention.

The previously known arrangement is diagrammatically shown inFig. l. The switch contacts inserted in thehigh or low frequeucy circuit of thetransmitting station J are actuatedfrom the distant receiving station Bby means of a key M, through the intermediation: of the line F and the electro magnet I.

In contradistinction thereto. the present invention has for its object to arrange in the transmitting station the means for the direct listening to or registration of the signals received at the receiving station or of my inbeing capable of utilizing thetransmitting station for their own purposes Further, the chi-ct of the station having at his disposal several completely independcut and simultaneously operating listening apparatuses. may by reason of having imme diate control of the operators and of the apparatuses dispose of them according to requirements. by concentrating them either on one and the same particularly important or difficult communication or on several; different communications.

First of all it allows of the watch- 1 Moreover, this. system of connections rcquires a minimum of auxiliary lines for the transmission of orders.

Finally a good solution of the transmission at a distance of the acoustically received. signals leads to the contemplation of a supplementary concentration in a central ofiice independent of the wireless stations of all the signals received at the different receiving stations of a country orot' a portion thereof. c

, The transmission of the undulatory currents constituting the signals to be received or registered, from the receiving station to the transmitting station, and if desired from the receiving station to an independent central office of the system. is eifected by means of the lines F,, F, (Fig. 3). One of the extremities of each line is suitably connected. as hereinafter more particularly referred to. to the proper receiving appara tns, the purpose of which is, to transform the Hertzian waves into oscillations capable of being read or registered; the other extremity' thereof is connected to the telephone or registering apparatus of the transmitting station or. of. the central ofiice. I I

Fig. 2 shows theprinciple of the gronp ing of the stations and apparatus of a duplex system. A is the transmitting station. and

B the receiving station; The station B mainly comprises an opener closed receivinc aerial D, actuating the group E of tuning circuits, amplifiers, detectors, ete.- constituting the ordinary receiving apparatus.

At the outer end of the group there is provided a telephone T in order that supervising operator may tune the receiving, apparatus, and an arrangement K hereinafter more particularly referred to serving to connect the receiving station to the connecting line F which consists of twoconductors having substantially the same elec trical constants, that is, resistance,'i.nductance and capacity. The other end of the line F reaches the transmitting station, where it actuates the telephones or registerinc apparatus G, which are employed, the latter being placed not far from the transmitting key M.

It is to be understood that several receiving stations B, B (Fig. 3) may be placed in proximity to the transmit-tine station A and that they may supply not only the transmitting station A' of "the duplex system throufrh lines F and F respectively. but that they may also supply a central o iice common to the stations ll and B and to the other stations, which are more or less distant. This general arrangement is shown in Fig. 3.-

In order to ensure the good working. of such an installation. a certain number of conditions must be fulfilled.

(a) The problem is evidently easier to solve when the received signals are more intense, and the distance over which they ar transmitted by wire is smaller.

These two conditions are obtained simultaneously by arranging the duplex system according to one of the methods described in applicants co-pending application for Letters Patent, Serial No. 318 368. til ed Aug. 18, 1918. These arrangements permit o,t. imparting to the call-listening receiver a considerable sensitiveness and, consequently, greatly increasing the intensity of the received signals without such signals being in any way. disturbed by the transmission from the station which, maybe only a few thousand, or even a few hundred. metres distant.

From this point of View the. problem is completely solved.

b.) The electric constants of the lines F of the listening or registering apparatus G of the connection K and oi; the proper receiving apparatus E must he adapt ed so, as to suitably correspond to each other. This may be accomplished in accordance with. known principles, as long as, the dis: tance AB is not greaterthan 2, or 3. km. he appar tu i eph n s m l fi r n fo me etc-i. f any an a mo e ployed in wireless telegraphy may be em-, ployed. These. principles are so well known to engineers Working in -the art-s oftelegraphy and. telephony that no explanation of them is required in order to enable those skilled. insuch arts to practice applicants invention. that in accordance with one of; these principles. the impedance of the instrumentalities at each end of the line F, should be substantially equal to the surge impedance of the line. In other words. it the suree impedance of the line F were 500 ohms. the impedance of the device G at the station A should be substantially equal to 500 ohms. and the aggregate impedance ot the devices K. T and E at the station B should alsohe substantially equal to 500 ohms. The basis of this principle is the prevention of reflection of energy along the line F,.

(c) The presenceoi the lines F. end ing' at the receiving station B should not interfere with the duplex service. However. the more or less energetic action of the transmitting' apparatus A upon these lines will produce therein a certain number forced oscillations. so that there is the risl; that the wires will transmit the disturbing effect of the transmitting apparatuses enas the interior oi the receiving room. T'F this danger is not met by great precaution.

all the improvements incorporated in the construction of the proper receiving" apparatus willfbe render-ed useless, and the duplex working made impossible.

It is first to be noted. that the action oi thetransmittino; aerial on a line F may be analyzed as follows: (see Fier, 43

It produces an electromotive force oi circulation X, shown by the arrows in full lines in Fig. 4 and two equal electromotive forces YY of they same direction (arrows in dotted lines) actingv upon the two wires of the line considered as an open aerial.

The amplitude of X and Y may be attenuated by burying the line F on part or its course. The subterranean part must not. however, exceed a certain length.v otherwise the intensity of the signals would; be. too much weakened. For this reason. only the two ends of theline over a distance ot a few hundred metres are buried. By this simple measure, the following advantages are attained :The aerial partof the line. F is removed from the transmitting station, and the more powerful high, frequency oscillations are almost, entirely absorbed in the ground, betore their arrival. at the receiving station. This arrangement is much more efiicien-t th an the placingin parallel between the ground and the. wires of the line. of two large nondistribi ted capacities.

A further attenuation of the force X may be obtained. by a, counter-induction arrangement of the aerial part of the line. that is to say by crossing from distance to distance the two wires so as to annul the total; enclosed flux. By judiciously using this precaution,

It may be mentioned. however,

X may be rendered negligible. The remaining disturbance could then be due only to the components Y.

Consequently, what remains to be done. is to find a means of coupling K between the wires F and the receiving box, such that the disturbances due to Y shall not betransmitted to the receiving apparatus. This may be accomplished in various ways.v and among numerous solution the following three may be mentioned. by way oi. example.

In Fig, 5. the coupling is effected by a transformer or av system of transformers lQ. The winding which acts as primary relatively to the disturbances coming from the line F s earthed at a suitable point. By thismeans a great reduction in the average potential of this winding is obtained. which attenuates the effect due to the electrostatic coupling between P and As to the induction eilt'ect produced. on the winding P b the leakage currents i 5,. due to the forces Y and flowing to the ground. it may evidently be nil it the carthing point is properly chosen.

In Fig. 6. the connection is effected by an acoustic coupling. The undulating current constituting the signal to be read or regis tercd actuates av vibrating membrane Q through the intermediation of an electromagnet P. which may or may not. be polarizcd. lhe said membrane actuates in its turn a microphone S. placed at the end of the connecting l ne Usually, the receiving ap aratus adapted to work on the duplex system i enclosed in a Faraday cage which protects the very sensitive parts of the apparatus. such as the am lifier. against the direct action of the adjacent transmitting station. The continuous wall of this cage is r placed in the part lying bet-ween the plates Q and S b a wire gauze R with rather small mesh. which does not stop the acoustic transmission. but acts against any electrostatic effeet between the line F and the receiving apparatus.

Fin. 7 illustrates an electromechanicalcoupling in which the vibrating plate S of the microphone is directly actuated by the electro-magnet P. The gauze R may be replaced in this arrangement by a very thin sheet of non-magnetic metal.

It will be obvious that in all these arrangements. an amplitving; relay of any suitable character may be inserted on the line F.

Having described my invention. what I claim is:

1. In a duplex wireless system. composed of transmitting station and a receiving station having receiving apparatus intended to work simultaneously with the transmitting apparatus, means at said transmitting station for indicating the received signals. a

work simultaneously with the transmitting apparatua means at said transmitting sta tion for indicating the received signals and a connecting line between said indicating means and the receiving apparatus of the receiving station said connecting line being; coupled to the receiving apparatus through a coil grounded at an intermediate point.

3. In a duplex wireless system, composed of a transmitting station and a receiving station having receiving apparatus intended to work simultaneously with the transmitting apparatus. means at said transmitting station for indicating the received signals and a connecting line between said indicating means and the receiving apparatus of the receiving station, said connecting line being crossed at intervals for decreasing the ctt'ect of said transmitting station on the receiving apparatus.

4. In a duplex wireless system a transmitting station and a receiving station adapted to work simultaneously, means at said transmitting station for indicating rcceivcd signals connecting lines for joining the indicating means with said receiving station. said connecting linesbeing crossed at at intervals and havinga substantial portionv adjacent the transmitting station buried in the earth and means for coupling said connecting lines to said receiving station comprising a coil. grounded intermediate its ends.

5. In a duplex wireless system a transmitting station and a receiving station adapted to work simultaneously, means at said transmitting station for indicating received signals, connecting lines for joining the indicating means with said receiving station, said connecting lines being crossed at in tervals and means for coupling said con necting lines to said receiving station com prising a coil grounded intermediate its ends.

HENRI JEAN JOSEPH MARIE zle REGNAULD dc BELLESCIZE. 

